This invention relates to a laminate and more particularly to a strongly bonded, multi-layered spray-suppression device having a balance of service properties enabling its use over a broad range of climatic conditions.
As disclosed in U.S. Pat. No. 3,899,192, laminated spray-suppression devices for mounting adjacent wheels of moving vehicles are known in the prior art. In such patent a grass-like layer is shown facing the rotating wheel and this has proven especially effective in absorbing impinging spray from a wet roadway surface and allowing it to drain pack onto the pavement.
As disclose U.S. Pat. No. 4,361,606, a performance problem has occurred with such devices when formed of integrally fused low density polyethylene and high density polyethylene layers. More specifically, cracks generated in the grass-like layer of low density polyethylene which has a pronounced tendency to embrittle at temperatures on the order of about minus 20.degree. F. (minus 29.degree. C.) propagate through to the high density polyethylene backing layer. This results in fracture of the laminate through its entire thickness even though the relatively good low temperature ductility of the high density polyethylene would be expected to be adequate to inhibit the crack from perpetrating through such high density polyethylene layer. As disclosed in such application, irradiation of the composite overcomes the problem and provides the device with the desired balance of low temperature properties.
However, though irradition has been used it has deficiencies. More specifically, rather high dosages are necessary to alleviate cracking and this represents significant expense. Moreover such dose levels provide an undesirable yellow tinge to the laminated product. In addition, catalyst residues and various processing additives present in the polyethylene of the various layers may be activated by the irradiation and react over long term periods to cause deterioration in the very properties intended to be enhanced.